This invention relates generally to the field of power impact tools and, more particularly, to a power impact tool torque apparatus which adjusts torque.
Power impact tools (e.g., pneumatic, hydraulic, electric, etc.) are well known in the art. In general, torque applied to a workpiece (e.g., nut, bolt, etc.) is the same regardless of the direction of rotation of the power impact tool. Frequently, however, greater torque is required to crack seized nuts or loosen nuts in the reverse direction of rotation than in the forward direction. Similarly, often a workpiece will have a torque specification which spells out the maximum amount of torque allowed for tightening workpieces in order to avoid overtorquing; and, thereby stripping a threaded workpiece during tightening.
Currently, a separate torsion bar kit may be purchased and attached to the power impact tool. These torsion bar kits can reduce the torque ultimately transmitted to a workpiece from the amount of torque that the power impact tool (i.e., motor and clutch combination) puts out. Unfortunately, a shortcoming of these torsion bar kits is that they are manufactured and marketed for attachment to a single make, model, and size power impact tool. That is, while they technically reduce the torque output of a power impact tool by a fixed quantity of torque, the user is only informed of the ultimate amount of torque applied to a workpiece by the specific power impact tool and torsion bar kit combination. For example, if the user takes a torsion bar kit sold as a xe2x80x9ctwenty foot-pound torsion bar kitxe2x80x9d and attaches it to the correct, applicable power impact tool, twenty foot-pounds of torque will ultimately be applied to the nut. Thus, in this case, suppose the specified, applicable pneumatic wrench is rated at one hundred foot-pounds of torque output, the amount of torque ultimately applied to a nut by the impact wrench would ultimately be twenty foot-pounds in either direction of rotation. This is because this specific torsion bar kit, although marketed and labeled as a xe2x80x9ctwenty foot-pound torsion bar kitxe2x80x9d is not automatically reducing the torque ultimately applied to a nut to twenty foot-pounds, but is actually reducing the torque output of the impact tool to that applied to the workpiece by eighty foot-pounds (i.e., 100 minus 80). Unfortunately, as is often the case, the user will take this same torsion bar kit and attach it to a different impact tool. For example, the user will then attach this same xe2x80x9ctwenty foot-pound torsion bar kitxe2x80x9d to a torque wrench, rated at one hundred forty foot-pounds of torque output. The user mistakenly believes that this combination of torsion bar kit and power torque wrench again results in twenty foot-pounds of torque being ultimately applied to a workpiece. This is incorrect. In fact, this new combination results in sixty foot-pounds being applied to the workpiece (i.e., 140 minus 80). Again, this is because the torsion bar kit reduces torque output by eighty foot-pounds. Frequently, because the user does not know what the torque output rating of a particular power impact tool; the user is constantly moving the torsion bar kit from one power impact tool to another; and, the user believes that the torsion bar kit automatically reduces torque applied to a workpiece to a fixed amount, ultimately results in the user being unable to determine the amount of torque being actually applied to the workpiece. As a result, workpieces may be overtorqued or undertorqued, ultimately being destroyed in the process. These aftermarket torsion bar kits suffer from several shortcomings, including that the exact total torque transmitted to a workpiece is frequently unknown and the amount of torque applied to the workpiece is the same in both directions of rotation.
Accordingly, there is a need in the field of power impact tools for ways to provide more predictable amounts of torque ultimately applied to a workpiece in both directions. Additionally, there is a need for an apparatus to provide greater torque in a single direction of rotation in a more predictable quantity for use with power impact tools.
The present invention provides an apparatus and method for use with power impact tools.
A first general aspect of the invention provides an apparatus for a power impact tool comprising:
a torsion bar;
an outer tube operatively attached to said torsion bar, said outer tube having recesses shaped to allow greater torque transmission in a first direction than in a second direction.
A second general aspect of the invention provides an apparatus comprising:
an outer tube having a plurality of inwardly extending driving surfaces;
a torsion bar with a plurality of receiving surfaces on the exterior thereof;
wherein said driving surfaces are in driving engagement with said receiving surfaces upon rotation in a first direction only.
A third general aspect of the invention provides an apparatus comprising:
a torsional spring with a plurality of extensions on an exterior thereof;
an outer cylinder having a bore with a plurality of inwardly extending recesses on an interior surface thereof;
wherein said plurality of inwardly extending recesses allow greater purchase with said torsional spring upon a nut loosening rotation.
A fourth general aspect of the invention provides a power impact tool comprising:
a housing;
an air motor within said housing;
a torsion bar operatively attached to said air motor; and
an outer tube operatively attached to said torsion bar, said outer tube having recesses shaped to allow greater torque in a first direction than in a second direction.
A fifth general aspect of the invention provides a power impact tool comprising:
a housing;
an air motor contained within said housing, wherein said air motor provides a first torque output; and
a torque control system comprising an outer tube surrounding a torsion bar, wherein said torque control system is operatively attached to said air motor, wherein said torque control system changes said first torque output to a second torque output.
A sixth general aspect of the invention provides a method of making an apparatus for a power impact tool comprising:
providing a torsion bar; and
attaching an outer tube to said torsion bar, said outer tube having recesses shaped to allow more torque transmission in a first direction of rotation than in a second direction of rotation.
A seventh general aspect of the invention provides a method of using a power impact tool apparatus comprising:
Providing a torsion bar;
attaching an outer tube to said torsion bar, said outer tube having recesses being shaped to allow more torque transmission in a first direction of rotation than in a second direction; and
attaching said torsion bar to a workpiece.
The foregoing and other features of the invention will be apparent from the following more particular description of various embodiments of the invention.